Added a maintenance mode notification to the readme.

Author: tillig

README.md

@@ -4,6 +4,8 @@
 
 [![Build status](https://ci.appveyor.com/api/projects/status/7cy42ia922we7v3w?svg=true)](https://ci.appveyor.com/project/Autofac/autofac-extras-domainservices)
 
+**MAINTENANCE MODE**: This package is in maintenance-only mode. Bug fixes may be addressed and Autofac compatibility may be checked but no new features will be added.
+
 Please file issues and pull requests for this package in this repository rather than in the Autofac core repo.
 
 - [Documentation](http://autofac.readthedocs.org/en/latest/integration/ria.html)